Fig. 2. Phox2b induces Cash1 in combination with Nkx2.2. In situ hybridization on transverse sections of the spinal cord with Cash1 (A',B',C',D') and Ngn2 (A'',B'') probes at 6 (A-A'') and 20 (B-B'') h.a.e. of mPhox2b plus mouse Nkx2.2 (0.5 mg/ml) or at 20 h.a.e. of 0.5 mg/ml (C,C') or 1 mg/ml (D,D') mouse Nkx2.2 alone. The extent of transfection is shown by in situ hybridization with a GFP probe (A-C) or by GFP fluorescence (D). Mouse Nkx2.2 (0.5 mg/ml) does not induce Cash1 (C'), but does so in combination with mPhox2b (B'). Ngn2 is repressed in the area where Cash1 has been induced (B''). At 1 mg/ml, mNkx2.2 transfection alone elicits a modest increase in Cash1 expression (D'). No effects on Cash1 or Ngn2 expression were observed at 6 h.a.e. (A' and A'').